1. Field of the Invention
The invention relates to a sealing apparatus for a semiconductor wafer, and a method of manufacturing a semiconductor device by using the sealing apparatus. More particularly, the invention relates to a method of manufacturing a Chip Size Package (CSP) whose size is similar to that of a semiconductor chip contained therein by using the sealing device.
2. Description of the Related Art
Recently, it has been required to shrink electric devices. To meet the requirement, it is also required to downsize a semiconductor device. As one of the solutions to satisfy these requirements, it has been proposed to form a semiconductor device having a chip size package (CSP) structure. The size of the semiconductor device having the CSP structure is almost the same as that of the semiconductor chip.
The method of forming the semiconductor device having the CSP structure includes a step for forming a plurality of semiconductor elements on a semiconductor wafer, a step for setting the semiconductor wafer in a mold, a step for sealing a surface of the semiconductor wafer on which the semiconductor elements are formed by a thermoset resin, a step for removing the semiconductor wafer sealed by the resin from the mold, a step for polishing the resin on the semiconductor wafer until electrodes formed on each of the circuit elements are exposed, and a step for dividing the semiconductor wafer into semiconductor devices having the CSP structure. If necessary, external terminals, such as soldering balls, may be formed on the exposed electrodes. Specifically, in the step for sealing a surface of the semiconductor wafer on which the semiconductor elements are formed by the thermoset resin, the thermoset resin is introduced on the surface of the semiconductor wafer from one side, and is expanded on the entire surface of the semiconductor wafer
However, according to the process for manufacturing the CSP-type semiconductor device described above, since the thermoset resin is introduced on the surface of the semiconductor wafer from one side, and is expanded on the entire surface of the semiconductor wafer, it takes a time to spread the thermoset resin on the entire surface of the semiconductor wafer. Although the thermoset resin is melted by heat, the melted resin is re-solidified with the course of time. Thus, it is necessary to spread the thermoset resin on the semiconductor wafer from one side to the other side before the melted resin is solidified so that it is required to accelerate the flowing speed of the resin. On the other hand, there are many sensitive semiconductor elements formed on the surface of the semiconductor wafer where the resin covers. Thus, if the melted resin flows on the surface of the semiconductor wafer with high speed, the resin catches air near these elements. As a result, void is created in the resin.